Electrolytic device



July l2, 1932. f H. o. SIEGMUND ELCTROLYT IG DEVIC E Filed oct. 25, 192e Patented July `12, 1932 UNITED STATES PATENT ori-ICE HUMPHREYS 0. SIEGMUND, OF WEST ORANGE, NEW JERSEY, ASSIGNOR TO BELL TELE- PHONE LABORATORIES, INCORPORATED, F `NEW YORK, N. Y., A CORPORATION OF NEW YORK ELEc'rBoLY'rIC DEVICE Apncauon ined october 25, 1926. 4senin No. 144,000.

This inventionrelates to electrolytic condensers.

In accordance with this invention there is provided an electrolytic condenser which is 5 small in size, which will operate satisfactorily even though not maintained in an upright position, one in which the period over which the electrical properties remain substantially constant is increased, and one from which the l0 danger of damage from a broken container is small.

The invention in its preferred form is an electrolytic condenser the electrolyte of which is of jelly-likeconsistency and is composed of sodium silicate and a dilute solution of sulphuric acid in such proportions that the desired'consi-stency is obtained. The filmforming kelectrode is of tantalum. The con tainer 1s provided with a non-liquid seal 2O which normally prevents the escape of vapor from the space above the surface of the electrolyte.

It has been found that by employing an electrolyte of the consistency mentioned above, several marked advantages are obtained, as explained below.` i

The electrolytes of electrolytic. devices as ordinarily constructed are of such nature that slow evaporation of the electrolyte oc- 33 curs, unless preventive means are provided., Such ineens commonly consists ot a layer of oil or other liquid upon the surface of the electrolyte. This is fairly eilcctive but inconvenient and adds to the likelihood ot 35 damage to surrounding apparatus and to the clothing ci: the operator if breakage of the container occurs, as often does. rihe pie vention ci slow concentration c: the 'electrolyte due to evaporation becoi Js i3 portance in an electrolytic condenser, since changes in capacity and resistance vary the operation of the circuit in which the con.- denser is placed and frequent checks upon the electrical properties ol" the condenser may become necessary. Moreover, it may be necessary to replace the condenser after a time which is shorter than the lite of' a condenser o the solid dielectric form.

Again, if electrolytic condensers are to compete successfully with ordinary condensers of the solid dielectric type, the nuisance of spilled liquid resulting from broken or cracked containers must be eliminated.

Moreover, it would be Very desirable to have eondensers of a ki nd to permit them to be used successfully in other than an upright position. f

l In accordance with this invention these requirements are satisfactorily met and it becomes feasible to substitute electrolytic condenscrs Jfor some of those of the usual type in the telephone plant, for example, the three main requirements are si1nultaneously met by the use of an electrolyte Which has the consistency' of stiff jelly and which is otherwise suitable. Evaporation takes place very slowly from such an electrolyte, so that constancy of electrical characteristics is more nearly approached and the use ful life period extended. y Furthermordby employing tantalum (or a metal of similar characteristics) as the film-forming electrode, the size of the condenser for a given capacity may be made small, which permits further reduction in the rate of evaporation and increase of useful life. A third feature tending toward the same end is the seal employed., This isl preferably of the type disclosed in Patent A655926 granted .lanuaryc 1928 to H.. 0. Siegmund, et al. Such a seal is normally gas tight hut opens to permitgases to escape when the gas pressure becomes great enmigh. This seal greatly assists in preventing' escape of vapor resulting from evaporation and so keeps down the rate of evaporation. Nevertheless, some 'vapor necessarily escapes with the gas. Thus it is seen that the jelly-like electrolyte and the seal and the kind ci electrode material employed all cooperate to enfect the. desired result. Mot-coiffer, an electrolyte of this type will retain its forni for long periods under mild 'forces tending 'to devoini il'. When the spar-.e below the seal in a con tainer is nearly although not quite filled with such an electrolyte. the container may be placed upon its side or in other positions without seriously affecting the operation of the condenser. if the container is broken, no spilling will occur.

`line 2-2 oi Fig. l.

'employ a sealing compoun The :form of electrolyte which lhas been found to meet the above mentioned require ments most successfully is one comprising sodium silicate and dilute siilpliuric acid in proportions to give the desired consistency.

A preferred embodiment of the invention is shown in tliedrawing in which:

Fig. l is a sectional View of a condenser in accordance witlrtlie present invention; and

Fig. 2 is a sectional View taken along the rrlie electrolyte 10, which,'as stated above, consists preferably of sodium silicate and a solution of sulphuric acid in such proportions that s. thick jelly-libe substance is formed, is placed in a container l1 preferp ably oi a material which 'does not readily react chemically with the constituents of the electrolyte and which is not a ilin forming metal. The positive ...or film forming electrode 13, l referably of tantaluni, is held' in position and is spaced from the container 11 by the separator 12 which is of an electrical insulating material not readily acted on by the electrolyte Ias, for instance, glass, porcelain or hard rubber. .In condensers which are to be employed in direct current circuits, the container l1 may be made 0f a conduct-A ing material that is not attacked chemical-l ly bythe electrolyte `so that it may serve as the negative electrode 'of the device. For example, lead' may be used with an electrolyte containing sulphuric acid and tin with many other electrolytes. A condenser forE use in alternating current circuits may be made by employing two 61m forming elec'-,4 trodes preferably both of tantalum.

The cover for the device consists of the cork le which is preferably impregnated with paran, and a layer 15 of a sealing com'- pound. In some cases it mais' be desirable to having a high melting point.

The resistance component of the condenser impedance may be made large, when desired, by employing an acid ofl lowconcentration in the electrolyte, widely spaced electrodes, a barrier of non-conducting material between the electrodes or any combination of these. A condenser the impedance of which has a high resistance component may be made by employing widely spaced electrodes and an electrolyte having a low acid concentration and conversely, a condenser the impedance of which has a low resistance component may be made by employing a highly concentrated acid in the electrolyte and positioning the electrodes in close proximity. For example, a condenser having a capacity of 1 microfarad andl a resistance of approximately 40 ohms at a frequency of 1000 cycles per second may be made by employing a tantalum electrode having a surface area of approximately 0.65 sq. in. and spaced approximately 0.1 from the negative electrode. The electrolyte for electrolyte of je ly-like consistency, containmg sul huric acid and sodium silicate, and a plura ity of electrodes at least one of which is of tantalum.

2. An electrolytic condenser comprising an electrolyte containing sodium silicate and a solution of sulphur-ic acid and having the consistenc of elly, and a tantalum film formin e ectr e.

in witness whereof I hereunto subscribe m9y26name this 22nd day of October A. D., 1

HUMPHREYS o. srnfninrno.v 

